In a manufacturing line for absorbent articles such as a disposable diaper, the following method is commonly used for manufacturing pull-on diapers: the end sections of the continuous sheet in the transverse direction are folded to be layered on a ventral part and on a dorsal part while the continuous sheet is transported in the transport direction, the continuous sheet being to be an exterior material of a disposable diaper, the transport direction being a direction in which the continuous sheet continues; then, both end sections of the continuous sheet are each joined; and thereafter a single-cut piece is cut and separates from the continuous sheet. For example, Patent Literature 1 discloses a method for manufacturing a pull-on diaper as follows: elastic members which are disposed being stretched in the transport direction of the continuous sheet (a ventral part and a dorsal part) are divided at certain intervals in the transport direction; and the ventral part and the dorsal part which are stacked are heat-sealed (welded) on the divided areas. And then, the ventral part and the dorsal part are cut and separated on the sealed areas.